/7XNPS52-89-051

NAVAL POSTGRADUATE SCHOOLMonterey, California

FALTER -- A Fault Annotation Tool

Timothy J. Shimeall

September 1989

Approved for public release; distribution is unlimited.

Prepared for:

Naval Postgraduate School

Monterey, California 93943

FedDocsD 208.14/2NPS-52-89-051

,3Y KFOX LIBRARY JU PS ~-Q « * 1 ' UO *

uRADUATE SCHOOL MMONTEREY, CALIFORNIA 9'6^

NAVAL POSTGRADUATE SCHOOLMonterey, California

Rear Admiral R. W. West, Jr. Harrison Shull

Superintendent Provost

This report was prepared in conjunction with research funded by the Naval Postgraduate School

Research Council.

Reproduction of all or part of this report is authorized.

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5 MonIToRiNg 6RgAnI2ATi6n REP6RT numBER(S)

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PEAforming 6Agani2ATi6nI REPoRT nuMBER(S)

NPS52-89-051

I namE 6E PERFORMING 6RgANIZaTi6N( >mputer Science Dept.

hval Postgraduate School

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7a. NAME 6F M6niT6Ring organization

Naval Postgraduate School

I ADDRESS (City, State, and ZIP Code)

!onterey,CA 93943

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Monterey, CA 93943

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O&MN direct funding

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TITLE (Include Security Classification)

VLTER -- A Fault Annotation Tool(U)

PERSONAL AUTH6R(5)-UMEALL, Timothy J.

TyPE 6P REP6RTProgress

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SUPPLEMENTARY NOTATIONTO

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89 September 26

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FIELD GROUP SUB-GROUP

18 SUBJECT TERMS (Continue on reverse if necessary and identify by block number)

Software Testing, Fault, Failure Region

ABSTRACT (Continue on reverse if necessary and identify by block number):ALTER is a program that supports the process of determining the effect of a program defect on the local

ogram state. FALTER also provides the capability of recording the effect by annotation of the program

mtrol flow graph. FALTER is one of a series of four tools that work in an integrated fashion to analyze

iscal programs to determine the failure regions associated with identified faults in the programs. The

inotated control flow graph produced by FALTER will used as input by the program SPACER, and shall be

istomized for such usage. The users may access REACHER, FALTER and SPACER through a screen-

iented user interface called VIEWER. Beyond the failure region analysis FALTER may be useful in

search that examines the distribution of faults in program source code, and in efforts that examine the

roneous transformations induced by faults.

DISTRIBUTION/AVAILABILITY 6F ABSTRACT3 UNCLASSIFIED/UNLIMITED fj SAME AS RPT. fj DTIC USERS

a NAME OF REsP6nSIBLE INDIVIDUALShimeall, Timothy J.

21. AbsTRacT sEcuRiTy cUssiFicATi6N

UNCLASSIFIED22c. 6FFlCE SYMBOL52Sm

22b. TELEPHONE [Include Area Code

(408) 646-250$

FORM 1473, 84 MAR 83 APR edition may be used until exhausted

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Environment for Failure RegionAnalysis:

FALTER » A Fault Annotation Tool

Timothy Shimeall

Computer Science Department (Code 52Sm)

Naval Postgraduate School

Monterey CA 93943

25 September 1989

Table of Contents1. Introduction 2

2. Data Descriptions 4

3. Functional Requirements 6

4. Subsets and Supersets 11

5. Undesired Events 1

1

6. Glossary 12

List of Tables

1. FALTER Option Processing 6

2. FALTER Command Interpretation 8

List of Figures

1. Context Diagram for FALTER 2

2. FALTER Flow of Execution 7

1.0 Introduction: FALTER - A Fault Annotation Tool

FALTER is a program that supports the process of determining the effect of a

program defect on the local program state. FALTER also provides the capability of recording

the effect by annotation of the program control flow graph (generated by REACHER).

In at least the initial release of FALTER, the onus of derivation of the fault conditions

will fall on the user. It is therefore important that the user of FALTER be a knowledgeable

researcher, with experience in faults and their description.

FALTER is one of a series of four tools that work in an integrated fashion to analyze

Pascal programs to determine the failure regions associated with identified faults in the

programs. The annotated control flow graph produced by FALTER will used as input by the

program SPACER, and shall be customized for such usage. The users may access

REACHER, FALTER and SPACER through a screen-oriented user interface called

VIEWER. Figure 1 provides a context diagram for this use of FALTER.

Beyond the failure region analysis FALTER may be useful in research that examines

the distribution of faults in program source code, and in efforts that examine the erroneous

transformations induced by faults.

FALTER shall be written in C for use under UNIX 4.3 BSD. Future versions may be

transported to other operating systems and versions of BSD. Future versions may also be

constructed that deal with other input languages, in particular Ada (trademark, DoD AJPO).

This document contains all requirements for FALTER. Section 2 is a description of

the input and output data for FALTER. Two forms of description are used to describe the

data. Data entered or generated in a specific format is described using a BNF-style

VIEWER ,.. Display/Commands

Fault/Loc

Conditions

REACHER Augmented

Control Flow

Graph

Figure 1 : Context Diagram for REACHER

-2-

description, with non-terminals in italics, terminals in bold, explanations of non-terminals in

normal print and alternatives definitions are indicated by the vertical bar 'I*. Data entered or

generated with specific components of information are described in a record-style format.

Section 3 is a list of all of the functional requirements, including a description of the

response to each possible program input. Terms found in the Glossary are {delimited by

exclamation points!. /Input variables/ are delimited by slashes. //Output variables// or

portions thereof are delimited by doubled slashes. $Symbolic Value References$ are

delimited by dollar signs. In this section, the verb "shall" is used to indicate required

behaviors for FALTER. The verbs "will" or "is" is used to indicate necessary or

desirable actions that occur beyond the control of FALTER (e.g., user actions). The verb

"may" is used to indicate optional or alternative actions.

Section 4 identifies all acceptable subsets and foreseen supersets(extensions) to the

basic functionality described in sections 2 and 3.

Section 5 identifies the foreseen undesired events that may occur during FALTER 's

execution and describes responses to these undesired events. Omitted from this section are

events that may occur during FALTER's execution, but that FALTER cannot respond to.

Duplicatively included in this section are all error messages produced by FALTER and the

conditions under which FALTER will generate these messages.

Section 6 is a glossary of defined terms used in this document. In the text of this

document, each defined term appears delimited by exclamation points. These defined terms

may be looked upon as text macros, and these terms should be read in context.

-3-

2.0 Data Descriptions

Input

1

.

Augmented Control-Flow Graph (/ACFGHDR/, /ABKHDR/, /ACFG/)

(See REACHER Requirements Document)

2. Fault Conditions (/FaultCond/)

Most faults affect only selected portions of the local software state, and the affect

produces an erroneous state only under specialized conditions. Thus, the fault is an

implication:

fault-cond ::= ( selection-cond ) and ( error -cond ) •> ( error-transform )

where

selection-cond is a boolean expression selecting the affected portion of the local

state.

error-cond is a boolean expression selecting the conditions under which the

error-transform occurs.

error-transform is a boolean expression describing the logical transformation of

the system state.

3. Location Conditio (/LocCond/)

Most faults may be attributed to specific portions of the program source code. However,

some faults may be more distributed in the source. As such, it is useful to provide for a

grammar to describe the location of a fault.

loc-cond ::= Integer I Integer .. Integer I Integer .. Integer given loc-selection

where

Integer is a normal Pascal integer (non-negative)

loc-selection is a Pascal boolean expression

-4-

Output

1. Faulted Control-Flow Graph (//FCFGINFO//)

(Similar to /ACFGHDR/, /ABKHDR/ referenced above)

The format of this output will be specialized to be compatible with SPACER'S expected

input.

1. FCFG Header Info (//FCFGHDR//)

Field Acronym Value

Number of Graphs //FHLEN// Integer

Graph Data //FHPROCS// List of //FBKHDR//

Program Name //FHPGRM// String

2. FCFG Block Header Info (//FBKHDR//)

Field Acronym Value

Block Name //FBKNAME// String

Number of Return Locations //FBKNUMRET// Integer

Return Locations //FBKRET// Listof/ACFG/

Entry Conditions //FBKREACH// //ReachCond//

Block Nodes //FBKGRPH// /ACFG/

Number of Subsidiary Blocks //FBKNSUBS// Integer

Subsidiary Blocks //FBKSUBS// List of //FBKHDR//

Declaration Text //FBKDECL// String

Number of Faults //FBKFNUM// Integer

Fault Starting Points //FBKFLOC// list of /ACFG/

Fault Conditions //FBKFCON// list of //Conditional//

Fault Information //FBKFDATA// list of //Faultlnfo//

where //Conditional// is a Pascal Boolean expression, and a new structure //Faultlnfo//

has the following fields:

Field Acronym Contents

Fault Identification //FID// String

Fault Description //FDESC// String

Violated Specification Portion //FVIOL// String

Fault Type //FTYPE// //FaultClass//

Fault Location //FLOC// /LocCond/

Fault Implication //FIMP// /FaultCond/

where //FaultClass// is the set $Overrestrict$, $LoopCond$, $Calc$, $Inital$, $Sub$,

$NoCheck$, $Branch$, $NoBranch$, $NoThread$, $NoReq$, $Order$, $Reverse$, $Data$

. Graph/Condition Prompts (//GCPrompt//)

Field Acronym Contents

Graph Location //GCLoc// /ACFG/

Graph Statement Text //GText// String

Graph Statement Comments //GComm// String

Graph Error Conditions //GErr// //Conditional//

3.0 Functional Requirements

3.1 Overview

FALTER prompts the user for the program section where the identified fault first

affects the execution (or equivalently, the procedure or function in which the program defect

may be corrected). Starting with the first statement of the routine, FALTER steps through

statement by statement, constructing a local state in a user-supervised manner. At the

point where the fault is identified, FALTER prompts the user with m each section of the local

state and requests transformations caused by the fault on that portion of the local state.

When all portions of the local state are dealt with, FALTER records the information in the

//FCFG// and exits.

3.2 Initial Processing

On program initialization, FALTER shall expect the name of a file (/InFile/) to be

passed as an argument, along zero or more execution options. FALTER 's response to the

options and use of /InFile/ are described in Table 1 below. Should the file named by /InFile/

not exit or not be readable by FALTER, then FALTER shall display the message: File not

fond and exit.

Option String Response

r !ReadFCFG!

o /OutFile/ //ResultFile// shall be set to /OutFile/

notr IReadACFG!

not o //ResultFile// shall be set to /InFile/

m /Module/ Module named in /Module/ shall be selected for processing

n /NodelD/ Node indicated by /NodelD/ shall be selected as current

node

Table 1 -- FALTER Option Processing

3.2.1 IReadACFG! -- /ACFG/ Input

In the initial execution of FALTER to annotate a particular fault, FALTER shall read

in the /ACFG/ generated by REACHER and augment the /ACFGHDR/ and /ABKHDR/structures to form //FCFGHDR// and //FBKHDR// structures. In each //FBKHDR// in the

//FHPROCS// list in //FCFGHDR//, the //FBKFNUM// field shall be set to 0; //FBKFLOC//,

//FBKFCON// and //FBKFDATA// all shall be set to an empty list, /ModSelect/ shall be

initialized to point to the first //FBKHDR// in //FCFGHDR//. /CurNode/ shall be initialized to

point to the first node in //FBKGRPH// and INewG!. If the m and/or n options are present,

/ModSelect/ and/or /CurNode/, respectively, shall be modified as described in Table 1.

3.2.2 IReadFCFG! -- //FCFG// Input

To restore a saved //FCFG//, FALTER shall read the file named by /InFile/. The

format of this workfile is given in section 3.4. Should the file not be a complete and

consistent set of headers and //FCFG// FALTER shall display the message: Invalid

workfile format and prompt for an ACFG file to regenerate //FCFG//. Once the data is read

in, /ModSelect/ shall be initialized to point to the first //FBKHDR// in //FCFGHDR// and

/CurNode/ shall be initialized to point to the first node in //FBKGRPH//. If //FBKFNUM//>0then using the first elements in //FBKFLOC//, //FBKFCON// and //FBKFDATA//, lOldG!. If

//FBKFNUM//=0 then INewG!. If the m and/or n options are present, /ModSelect/ and/or

/CurNode/, respectively, shall be modified as described in Table 1. If no such //FCFG//

exists, FALTER shall display the message: Null workfile and exit.

3.3 //FCFG// Annotation

3.3.1 User Commands

Once an initial //FCFG// is available, either by restoring a previously saved //FCFG//

or by augmenting an /ACFG/ constructed by REACHER, FALTER shall allow the user to

traverse the //FCFG// and to add to the //FCFG// information on the faults present in the

program or program fragment represented by the //FCFG//.

The commands that FALTER shall support to allow the user this functionality are

described in table 2, along with a summary of the appropriate response. Supplementary

descriptions of the actions required of FALTER in response to these commands are given in

the sections that follow. Should the user enter a command that is not listed in table 2,

FALTER shall display the message: No such command and prompt the user again.

Should the user enter a command listed in table 2 without the listed arguments, FALTERshall display the message: Missing command arguments and prompt the user again,

ignoring the partial command. Should the user enter a command with more arguments than

those listed in table 2, FALTER shall display the message Ignoring string at end of

command, where string is a list of the extra arguments, and proceed to follow the command,

ignoring the extra arguments. Should the user enter a command with arguments that are not

of the appropriate type as listed in table 2, FALTER shall display the message: Invalid

arguments to command and prompt the user again, ignoring the attempted command.Figure 2 diagrams the FALTER flow of execution through the four classes of commands.

Partial

//Faultlnfo//

Browsing

Initial

//FCFG//

1

//GCPrompt// Fault Loc

Annotation

ACFG File

Fault Imp.

Annotation

-^

Partial

//FCFG//

//Faultlnfo//* Termination

FCFG File

Final

I//FCFG //

Result File

Figure 2 - FALTER Flow of Execution

Commanda

c /CommStr/

e /ErrCond/

f/LocCond/

g /ErrNum/

i /FaultCond/

m /Module/

n /NodelD/

1

P

r

s

t /Class/

w /Savefile/

v /SpecPart/

Table 2 - FALTER

Response

increment //FBKFNUM// for the current block, !DupF! and

using the new entry of //FBKFLOC//, //FBKFCON// and

//FBKFDATA//, lOldG!

set //GComm// to the value of /CommStr/

set //GErr// to the conditional expressed in /ErrCond/

set //FLOC// to /LocCond/

using the entry indicated by /ErrNum/ of //FBKFLOC//,

//FBKFCON// and //FBKFDATA//, lOldG!

set //FIMP// to /FaultCond/

set /ModSelect/ to the module named in /Module/

set /CurNode/ to the node with ID = /NodelD/

set /CurNode/ to the left child of current node

set /CurNode/ to the most recently visited node

set /CurNode/ to the right child of current node

Using the current //GCPrompt// IStoreG!

Set //FTYPE// to the value in //FaultClass//

save data structures in the file named in /Savefile/

Set //FVIOL// to the string in /SpecPart/

Terminate FALTER execution without saving data

structures

Command Interpretation

3.3.2 Browsing (a, c, e, g, m, n, I, p, r, s commands)

After construction or restoration of the initial //FCFG//, FALTER shall Idisplay! for

the appropriate /CurNode/ and prompt the user for a command. The command shall be

interpreted as described in table 2.

For the p, 1 and r commands, FALTER shall not change //GErr// and //GComm//, but

FALTER shall vary //GText// and //GCLoc// with the selected /CurNode/. If these commandsare entered and there is no previous node, left child or right child (respectively) then

FALTER shall display the message Cannot follow arc and prompt for a new commandwithout modification to the data structures..

For the n command, if there exists a node in the current module with /ACFGNUM/equal to the value specified, then FALTER shall not change //GErr// and //GComm//, but

FALTER shall vary //GText// and //GCLoc// with the selected /CurNode/. If there does not

exist a node in the current module with /ACFGNUM/ equal to the value specified, FALTERshall display the message Node not found and prompt for a new command without

modification to the data structures.

-8-

For the m command, if there exists a module described in //FHPROCS// or its

subsidiary //FBKSUBS// entries that has a name equal to the value specified, then FALTERshall IStoreG! and using the new /ModSelect/ !01dG!. If there does not exist such a module

description, FALTER shall display the message Module not found and prompt for a newcommand without modification to any data structures.

For the a command, FALTER shall increment //FBKFNUM// and add a new entry in

//FBKFLOC//, //FBKFCON// and //FBKFDATA//, duplicating the information from the prior

entry, if any. If there is no prior information, then !NewF!.

For the c command, //GComm// shall be set to the string given as an argument, with

no attempt at validation or format checking of the string.

For the g command, if the argument given is in the range 1...//FBKFNUM//, using the

//FBKFNUM// for /ModSelect/, then FALTER shall use the designated entry of

//FBKFLOC//, //FBKFCON// and //FBKFDATA// and lOldG!, discarding the previous value

of //GCPrompt//. If the argument given is 0, then using /ModSelect/ !NewG!. If the argument

given is less than or greater than //FBKFNUM// for /ModSelect/ then FALTER shall

display the message Value out of range and prompt for a new command without

modification of any data structures.

For the s command, if //FBKFNUM//=0 then increment //FBKFNUM//, !NewF! and

IStoreG!. If //FBKFNUM//>0 then the last entries of //FBKFLOC//, //FBKFCON// and

//FBKFDATA// used to set values of //GCPrompt// shall be updated to reflect the current

value of //GCPrompt//.

3.3.3 Fault Location Annotation (f, t commands)

Once a fault is located and informally described, the set of locations that reflect the

fault and the precise class of fault located may be annotated in the //FCFG/A The two

commands used in this annotation are the f and t commands.

For the f command, if the command argument does not parse to a recognizable

/LocCond/ structure then FALTER shall display the message Bad location format and

prompt for a new command without modification of any data structures. Otherwise, if

//FBKFNUM//>0 then the //FLOC// of the entry of //FBKFDATA// last used to set values of

//GCPrompt// shall be updated to the /LocCond/ specified in the command argument. If no

such entry exists, then !NewF! and using the new entry FALTER shall update //FLOC// to

the /LocCond/ specified in the command argument.

For the t command, if the command argument corresponds to one of the defined values

for//FTYPE// then FALTER shall replace any old value in //FTYPE// with the value

corresponding to the command argument. If the command argument does not correspond to

one of the defined values FALTER shall display the message No such fault type and

prompt for a new command without modification of any data structures.

3.3.4 Fault Implication Annotation (i, v commands)

Once the fault is isolated and classified, the implications of the fault in terms of what

portion of the specification is violated and what effect the fault has on the system state maybe annotated in the //FCFG//. The two commands used in this annotation are the i and v

commands.

For the i command, if the command argument does not parse to a recognizable

/FaultCond/ structure then FALTER shall display the message Bad implication format and

prompt for a new command without modification of any data structures. Otherwise, if

//FBKFNUM//>0 then the //FTMP// of the entry of //FBKFDATA// last used to set values of

//GCPrompt// shall be updated to the /FaultCond/ specified in the command argument. If no

such entry exists or //FBKFNUM//=0, then !NewF! and using the new entry FALTER shall

update //FIMP// to the /FaultCond/ specified in the command argument.

For the v command, if //FBKFNUM//>0 then the //FVIOL// of the entry of

//FBKFDATA// last used to set values of //GCPrompt// shall be set to the string given as an

argument, with no attempt at validation or format checking of the string. If no such entry

exists or //FBKFNUM//=0, then !NewF! and using the new entry FALTER shall set

//FVIOL// to the string given as an argument.

3.3.5 Final Processing (w, x commands)

Lastly, once the //FCFG// has been appropriately annotated, it may be written out in a

form useful for further processing. The precise format described below is intended to be

identical to the format expected of SPACER as input.

For the x command, FALTER shall request confirmation from the user, and if the

command is confirmed, cease execution.

For the w command, FALTER shall generate a file recording the //FCFG// in the

format used by SPACER as its input language, a LISP structure containing executable

analogues of the declarations and statements in the ACFG. The fault annotation will be

stored in a structure at the start of the file, with indicators of the apporpriate part of the

structure used as location pointers.

-10-

4.0 Subsets and Supersets

Supersets

1. Recognition of certain types of faults (i.e., missing logic faults) and specialized handling

of those types.

2. Consistency checking employing specialized forms of //FBKFCON//, //FDESC//, and

//FVIOL/A

3. Structure to //FVIOIV/ and //FDESC//

Subsets

1

.

Less sophisticated handling of fault location.

2. Less sophisticated handling of fault conditions.

3. No p command (use g as a work-around).

5.0 Undesired Event Handling

Error Messages:

Message Conditions of generation

Bad implication format Command argument unrecognizable as fault location

Bad location format Command argument unrecognizable as fault location

Cannot follow arc User requested transition along null reference in //FCFG//

File not found Missing or inaccessible input file.

Ignoring string at end of command Extra arguments on command entered by

user.

Invalid arguments to command Command entered with arguments of wrong

type.

Invalid workfile format Workfile is of wrong format for restoration, or data in

workfile is incomplete or inconsistent.

Missing command arguments Command entered by user without needed

arguments.

Module not found No module in //FHPROCS// or any //FBKSUBS// with

//FBKNAME// equal to that specified in the entered

command.

No such command Unrecognized command entered by user.

No such fault type Unrecognized fault type specified by command argument.

Node not found No node in current module with /ACFGNUM/ equal to that

specified in the entered command.

Null workfile No //FCFG// nodes in workfile.

Value out of range Command given with argument with improper value.

•11-

6.0

Idisplay!

!DupF!

!NewF!

!NewG!

lOldG!

IReadACFG!

IReadFCFG!

IStoreG!

Glossary

Print the /ACFGNUM/ in //GCLoc//, the //GText// equivalent to the

/ACFGTEXT/ in //GCLoc//, and any values set for //GComm// and //GErr/A

If//FBKFNUM//=1 then !NewF!. If//FBKFNUM//>1 then the entries of

//FBKFLOC//, //FBKFCON// and //FBKFDATA// corresponding to

//FBKFNUM// shall be set to be equal to their immediate predecessors in

each list, respectively (i.e., FALTER shall produce a duplicate of the

previous fault information in the new entry of these structures).

The new entry of //FBKFLOC// shall be set to /CurNode/; the new entry of

//FBKFCON// shall be set to false; In the new entry of //FBKFDATA//,

//FTD// shall be set to /ModSelect/ concatenated with the index of this

entry of //FBKFDATA//, //FDESC// and //FVIOL// shall be set to null

strings, //FTYPE// shall be set to $Data$, //FLOC// shall be set to the line

number corresponding to /CurNode/, //FIMP// shall be set to "(false) and

(false) -> (false)".

//GCLoc// shall be set to point to /CurNode/, //GText// shall be set to the

/ACFGTEXT/ in //GCLoc//, //GComm// shall be set to a null string and

//GErr// shall be false.

//GCLoc// shall be set to point to the corresponding entry of //FBKFLOC//,

//GErr// shall be set to the corresponding entry of //FBKFCON//, //GText//

shall be set to the /ACFGTEXT/ in //GCLoc//, //GComm// shall be set to

//FDESC// in the corresponding entry of //FBKFDATA//.

See section 3.2.1

See section 3.2.2

The corresponding entry of //FBKFLOC// shall be set to //GCLoc//, the

corresponding entry of //FBKFCON// shall be set to //GErr//, the

corresponding entry of //FBKFDATA// shall be set to have //FDESC// set

to //GComm//, and, if //FID// is previously empty, //FID// set to

/ModSelect/ concatenated with the index of this entry of //FBKFDATA//.

-12-

Distribution List

Defense Technical Information Center 2

Cameron Station

Alexandria, VA 22314

Library, Code 0142 2

Naval Postgraduate School

Monterey, CA 93943

Center for Naval Analyses 1

4401 Ford Ave.

Alexandria, VA 22302-0268

Director of Research Administration 1

Code 012

Naval Postgraduate School

Monterey, CA 93943

Chairman, Computer Science Department 1

Code 52

Naval Postgraduate School

Monterey, CA 93943

Shimeall, Timothy J 20

Code 52SmNaval Postgraduate School

Monterey, CA 93943

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